Who this guide is for
This guide is for companies that manufacture resin anchoring compounds — capsules, cartridges or bulk systems for rock bolting in mining and tunnelling. It is not installation guidance. SPR 301 RB is supplied as the liquid base resin for that manufacture; the finished anchoring product, its approvals and its installation instructions belong to its maker.
Where the base resin sits in a compound
A typical resin anchoring compound combines a mineral-filled polyester mastic with a separately packaged peroxide initiator, mixed at the moment of installation. The base resin sets the mastic’s reactivity, contributes to its viscosity alongside the filler, and becomes the binder of the cured anchorage.
SPR 301 RB is an isophthalic unsaturated polyester, supplied non-accelerated, with a typical viscosity of 2,000–3,500 cPs, specific gravity of approximately 1.12 and styrene of 35–39% by weight.
Questions the compound maker should bring
For a productive first discussion
- Which gel-time band the product needs: ultra-fast, delayed, or both in one system.
- Filler type and target loading, and target mastic consistency.
- Initiator paste chemistry and how it is packaged.
- Storage and shelf-life requirement of the finished product.
- The test regime the finished product must pass.
Published typical values
| Property | Rock Bolt Grade Resin (SPR 301 RB) |
|---|---|
| Chemistry | Isophthalic unsaturated polyester |
| Appearance | Viscous liquid resin |
| Viscosity (typical) | 2,000–3,500 cPs |
| Gel time / pot life (typical) | Ultra-fast grades 15 seconds–2 minutes · delayed grades 5–30+ minutes |
| Specific gravity / density (typical) | Approximately 1.12 |
| Styrene content (typical) | 35–39% by weight |
| Reference cure | BPO 7% + Cobalt Octoate approximately 0.4% — added separately during use |
| Source of values | 2026 catalogue; grade TDS |
Typical values, reproduced from each product’s own published data. They describe the liquid resin at its reference condition, not a finished part, and are not guaranteed limits.
The BPO reference cure
Unlike the MEKP-cured SPR 301 grades, SPR 301 RB is referenced with a BPO-based cure: BPO 7% with cobalt octoate approximately 0.4%, added separately during use. The two gel-time bands in the catalogue — ultra-fast grades at 15 seconds to 2 minutes and delayed grades at 5 to 30+ minutes — are measured against that system.
As with every peroxide and accelerator, BPO and cobalt must never be mixed directly with each other; each is combined with the resin separately.
What the compound maker owns
Filler grading, loading and treatment, the initiator paste, packaging, shelf life, set-time behaviour at underground temperatures, pull-out performance and any approvals are properties of the finished compound. The base resin is one qualified input. Trials should therefore be run on the full compound, at the temperatures the product will see underground, and against the product’s own test regime.